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1.
J Ultrasound Med ; 41(5): 1069-1076, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-34272888

RESUMO

OBJECTIVES: The physical exam component of a periodic health visit in the elderly has not been considered useful. Standard Medicare Wellness visits require no physical exam beyond blood pressure and most physicians perform limited exams during these visits. The objective of this study was to test the feasibility, potential benefit, and costs of performing a screening ultrasound (US) exam during Medicare Wellness visits. METHODS: A physician examiner at an academic internal medicine primary care clinic performed a screening US exam targeting important abnormalities of patients 65-85 years old during a Medicare Wellness visit. The primary care physician (PCP) recorded the follow-up items for each abnormality identified by the US examiner and assessed the benefit of each abnormality for the participant. Abnormality benefit, net exam benefit per participant, follow-up items and costs, participant survey results, and exam duration were assessed. RESULTS: Participants numbered 108. Total abnormalities numbered 283 and new diagnoses were 172. Positive benefit scores were assigned to 38.8%, neutral (zero) scores to 59.4%, and negative benefit scores to 1.8% of abnormalities. Net benefit scores per participant were positive in 63.9%, 0 in 34.3%, and negative in 1.8%. Follow-up items were infrequent resulting in 76% of participants without follow-up cost. Participant survey showed excellent acceptance of the exam. CONCLUSIONS: The US screening exam identified frequent abnormalities in Medicare Wellness patients. The assessed benefits were rarely negative and often mild to moderately positive, with important new chronic conditions identified. Follow-up costs were low when the PCPs were also US experts.


Assuntos
Programas de Rastreamento , Medicare , Idoso , Idoso de 80 Anos ou mais , Humanos , Medicina Interna , Exame Físico/métodos , Ultrassonografia , Estados Unidos
2.
BMC Pediatr ; 21(1): 327, 2021 07 27.
Artigo em Inglês | MEDLINE | ID: mdl-34315435

RESUMO

BACKGROUND: Infectious morbidity and mortality in the first week of life is commonly caused by early-onset neonatal Group B streptococcus (GBS) disease. This infection is spread from GBS positive mothers to neonates by vertical transmission during delivery and results in serious illness for newborns. Intrapartum prophylactic antibiotics have decreased the incidence of early-onset neonatal GBS disease by 80%. Patients labeled with a penicillin allergy (PcnA) alternatively receive either vancomycin or clindamycin but effectiveness is controversial. We evaluated the influence of a reported PcnA label versus no PcnA label on inpatient maternal and neonatal outcomes. METHODS: Our goal was to examine the relationship between a PcnA label, maternal and neonatal outcomes, and hospital costs. We collected retrospective data with institutional IRB approval from 2016 - 2018 for hospitalized patients who were GBS positive, pregnant at time of admission, ≥ 18 years of age, received antibiotic prophylaxis for GBS, were labeled as PcnA or non-PcnA, and completed a vaginal delivery. Patient characteristics and maternal/neonatal outcomes were examined. Statistical tests included calculations of means, medians, proportions, Mann-Whitney, two-sample t-tests, Chi-squared or Fisher's Exact tests, and generalized linear and logistic regression models. Significance was set at p < 0.05. RESULTS: Most PcnA patients were white, older, had a higher median body mass index and mean heart rate, and a greater proportion used tobacco than non-PcnA patients. In regression analyses, PcnA hospitalized patients received a shorter duration of antibiotic treatment than non-PcnA patients [incidence rate ratio (IRR): 0.45, 95% CI: 0.38-0.53]. PcnA patients were also more likely to have their baby's hospital LOS be > 48 h [adjusted odds ratio (AOR): 1.35, 95% CI: 1.07-1.69] even though the PcnA mothers' LOS was not different from non-PcnA mothers. Cost of care, mortality, intensive care, median parity, mean gravidity, and miscarriage were similar between the groups. CONCLUSIONS: In hospitalized obstetric patients, a PcnA label was associated with a shorter maternal course of antibiotic treatment and a longer neonatal LOS. Further prospective studies are needed to clarify the underlying reasons for these outcomes.


Assuntos
Hipersensibilidade a Drogas , Complicações Infecciosas na Gravidez , Infecções Estreptocócicas , Antibacterianos/efeitos adversos , Antibioticoprofilaxia , Hipersensibilidade a Drogas/epidemiologia , Hipersensibilidade a Drogas/etiologia , Hipersensibilidade a Drogas/prevenção & controle , Feminino , Humanos , Recém-Nascido , Transmissão Vertical de Doenças Infecciosas/prevenção & controle , Mães , Penicilinas/efeitos adversos , Gravidez , Complicações Infecciosas na Gravidez/tratamento farmacológico , Complicações Infecciosas na Gravidez/prevenção & controle , Estudos Retrospectivos , Infecções Estreptocócicas/tratamento farmacológico , Infecções Estreptocócicas/epidemiologia , Infecções Estreptocócicas/prevenção & controle , Streptococcus agalactiae
3.
Front Chem ; 3: 55, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26380255

RESUMO

Prostate cancer is the second leading cause of cancer-related deaths in US males, yet much remains to be learned about the role of inflammation in its etiology. We hypothesized that preexisting exposure to chronic inflammatory conditions caused by infectious agents or inflammatory diseases increase the risk of prostate cancer. Using the 2009-2010 National Health and Nutrition Examination Survey, we examined the relationships between demographic variables, inflammation, infection, circulating plasma C-reactive protein (CRP), and the risk of occurrence of prostate cancer in US men over 18 years of age. Using IBM SPSS, we performed bivariate and logistic regression analyses using high CRP values as the dependent variable and five study covariates including prostate cancer status. From 2009-2010, an estimated 5,448,373 men reported having prostate cancer of which the majority were Caucasian (70.1%) and were aged 40 years and older (62.7%). Bivariate analyses demonstrated that high CRP was not associated with an increased risk of prostate cancer. Greater odds of having prostate cancer were revealed for men that had inflammation related to disease (OR = 1.029, CI 1.029-1.029) and those who were not taking drugs to control inflammation (OR = 1.330, CI 1.324-1.336). Men who did not have inflammation resulting from non-infectious diseases had greater odds of not having prostate cancer (OR = 1.031, CI 1.030-1.031). Logistic regression analysis yielded that men with the highest CRP values had greater odds of having higher household incomes and lower odds of having received higher education, being aged 40 years or older, being of a race or ethnicity different from other, and of having prostate cancer. Our results show that chronic inflammation of multiple etiologies is a risk factor for prostate cancer and that CRP is not associated with this increased risk. Further research is needed to elucidate the complex interactions between inflammation and prostate cancer.

4.
BMC Health Serv Res ; 14: 563, 2014 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-25407745

RESUMO

BACKGROUND: Non-malignant chronic pain (NMCP) is one of the most common reasons for primary care visits. Pain management health care disparities have been documented in relation to patient gender, race, and socioeconomic status. Although not studied in relation to chronic pain management, studies have found that living in a rural community in the US is associated with health care disparities. Rurality as a social determinant of health may influence opioid prescribing. We examined rural and non-rural differences in opioid prescribing patterns for NMCP management, hypothesizing that distinct from education, income, racial or gender differences, rural residency is a significant and independent factor in opioid prescribing patterns. METHODS: 2010 National Ambulatory Medical Care Survey (NAMCS) data were examined using bivariate and multivariate techniques. NAMCS data were collected using a multi-stage sampling strategy. For the multivariate analysis performed the SPSS complex samples algorithm for logistic regression was used. RESULTS: In 2010 an estimated 9,325,603 US adults (weighted from a sample of 2745) seen in primary care clinics had a diagnosis of NMCP; 36.4% were prescribed an opioid. For US adults with a NMCP diagnosis bivariate analysis revealed rural residents had higher odds of having an opioid prescription than similar non-rural adults (OR = 1.515, 95% CI 1.513-1.518). Complex samples logistic regression analysis confirmed the importance of rurality and yielded that US adults with NMCP who were prescribed an opioid had higher odds of: being non-Caucasian (AOR =2.459, 95% CI 1.194-5.066), and living in a rural area (AOR =2.935, 95% CI 1.416-6.083). CONCLUSIONS: Our results clearly indicated that rurality is an important factor in opioid prescribing patterns that cannot be ignored and bears further investigation. Further research on the growing concern about the over-prescribing of opioids in the US should now include rurality as a variable in data generation and analysis. Future research should also attempt to document the ecological, sociological and political factors impacting opioid prescribing and care in rural communities. Prescribers and health care policy makers need to critically evaluate the implications of our findings and their relationship to patient needs, best practices in a rural setting, and the overall consequences of increased opioid prescribing on rural communities.


Assuntos
Analgésicos Opioides/uso terapêutico , Dor Crônica/tratamento farmacológico , Padrões de Prática Médica/estatística & dados numéricos , Prescrições/estatística & dados numéricos , População Rural/estatística & dados numéricos , População Urbana/estatística & dados numéricos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Pesquisas sobre Atenção à Saúde , Humanos , Masculino , Pessoa de Meia-Idade , Fatores Socioeconômicos , Estados Unidos , Adulto Jovem
5.
Prostate ; 74(10): 1059-67, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24854630

RESUMO

BACKGROUND: Protein glycosylation is a common posttranslational modification and glycan structural changes have been observed in several malignancies including prostate cancer. We hypothesized that altered glycosylation could be related to differences in gene expression levels of glycoprotein synthetic enzymes between normal and malignant prostate tissues. METHODS: We interrogated prostate cancer gene expression data for reproducible changes in expression of glycoprotein synthetic enzymes. Over-expression of GCNT1 was validated in prostate samples using RT-PCR. ELISA was used to measure core 2 O-linked glycan sialyl Lewis X (sLe(x) ) of prostate specific antigen (PSA), Mucin1 (MUC1), and prostatic acidic phosphatase (PAP) proteins. RESULTS: A key glycosyltransferase, GCNT1, was consistently over-expressed in several prostate cancer gene expression datasets. RT-PCR confirmed increased transcript levels in cancer samples compared to normal prostate tissue in fresh-frozen prostate tissue samples. ELISA using PSA, PAP, and MUC1 capture antibodies and a specific core 2 O-linked sLe(x) detection antibody demonstrated elevation of this glycan structure in cancer compared to normal tissues for MUC1 (P = 0.01), PSA (P = 0.03) and near significant differences in PAP sLe(x) levels (P = 0.06). MUC1, PSA and PAP protein levels alone were not significantly different between paired normal and malignant prostate samples. CONCLUSIONS: GCNT1 is over-expressed in prostate cancer and is associated with higher levels of core 2 O-sLe(x) in PSA, PAP and MUC1 proteins. Alterations of O-linked glycosylation could be important in prostate cancer biology and could provide a new avenue for development of prostate cancer specific glycoprotein biomarkers.


Assuntos
Mucina-1/metabolismo , N-Acetilglucosaminiltransferases/fisiologia , Antígeno Prostático Específico/metabolismo , Neoplasias da Próstata/metabolismo , Proteínas Tirosina Fosfatases/metabolismo , Fosfatase Ácida , Idoso , Glicosilação , Humanos , Antígenos CD15/fisiologia , Masculino , Pessoa de Meia-Idade , N-Acetilglucosaminiltransferases/genética , Antígeno Sialil Lewis X
6.
Front Biosci (Landmark Ed) ; 16(9): 3233-51, 2011 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-21622232

RESUMO

The selectins: E-selectin, P-selectin, and L-selectin are adhesion molecules that are crucial for binding of circulating leukocytes to vascular endothelium during the inflammatory response to injury or infection. Accumulated evidence indicates that selectins regulate adhesion of circulating cancer cells to the walls of blood vessels. Selectin ligands are transmembrane glycoproteins expressed on leukocytes and cancer cells that promote bond formations with selectins to mediate inflammatory processes. Selectins and selectin ligands also participate in signal transduction to regulate diverse cellular functions. Sialyl Lewis X (sLe(x)) and sialyl Lewis A (sLe(a)) tetrasaccharides are carbohydrate motifs displayed on protein or lipid scaffolds that are critical components of functional selectin ligands. Selectin binding to sLe(x) and sLe(a) present on colon, gastric, bladder, pancreatic, breast, and prostate carcinomas enhances distant organ metastasis. High expression of sialyl Lewis ligands on these cancers is significantly correlated with a poor post-operative prognosis. This review will focus on the roles of E-selectin and P-selectin in cancer progression. Understanding the role of selectins in cancer supports the development of novel selectin-based therapies to control metastasis.


Assuntos
Células Endoteliais/fisiologia , Metástase Neoplásica/fisiopatologia , Selectinas/fisiologia , Animais , Selectina E/fisiologia , Humanos , Inflamação/fisiopatologia , Ligantes , Modelos Biológicos , Selectina-P/fisiologia , Selectinas/química , Selectinas/genética , Transdução de Sinais , Microambiente Tumoral/fisiologia
7.
Cancer ; 117(19): 4493-505, 2011 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-21437888

RESUMO

BACKGROUND: The carbohydrate sialyl Lewis X (sLeX) is expressed on leukocytes and carcinoma cells and binds to selectins during inflammatory processes and early metastasis. Synthesis of sLeX depends on activity of enzymes, including α(1,3/1,4) fucosyltransferase (FucT-III). Tumor necrosis factor-α (TNF-α) up-regulates FucT-III, resulting in increased sLeX in the airways of patients with respiratory disease; however, the mechanisms that regulate sLeX in the inflammatory tumor microenvironment are not well understood. METHODS: The authors stably transfected human lung carcinoma cell lines with the FucT-III gene and exposed them to TNF-α to investigate its role in regulation of sLeX expression and selectin-binding ability using semiquantitative real-time polymerase chain reaction and flow cytometry. Cytokine expression was examined in transfected cells using chemiluminescent arrays and enzyme-linked immunosorbent assays, and invasion was studied using Matrigel assays and alterations in morphology. Human lung tissue arrays were analyzed for immunohistochemical detection of sLeX and neutrophils. RESULTS: Stimulation of FucT-III-transfected cells with recombinant human (rh) TNF-α up-regulated sLeX expression and increased E-selectin binding. Transfected cells secreted high levels of interleukin 8, growth-regulated oncogene-α, and mast cell proteinase-1. Cells exposed to rhTNF-α, neutrophil-conditioned media, and cultures with a 5:1 ratio of neutrophils to cancer cells had significantly increased sLeX expression and invasiveness and underwent nonadherent morphologic changes. In lung carcinomas, but not in normal lung tissues, 71% of tumors were highly positive for sLeX expression in areas of increased neutrophil infiltration. CONCLUSIONS: The current results indicated that neutrophils may be recruited to areas of FucT-III activity and sLeX expression in lung carcinomas to enhance the invasive and metastatic potential of lung cancer cells.


Assuntos
Carcinoma Pulmonar de Células não Pequenas/imunologia , Carcinoma Pulmonar de Células não Pequenas/patologia , Neoplasias Pulmonares/imunologia , Neoplasias Pulmonares/patologia , Neutrófilos/imunologia , Oligossacarídeos/metabolismo , Western Blotting , Carcinoma Pulmonar de Células não Pequenas/metabolismo , Selectina E/genética , Selectina E/metabolismo , Ensaio de Imunoadsorção Enzimática , Citometria de Fluxo , Fucosiltransferases/genética , Fucosiltransferases/metabolismo , Humanos , Técnicas Imunoenzimáticas , Neoplasias Pulmonares/metabolismo , Invasividade Neoplásica , Neutrófilos/metabolismo , Oligossacarídeos/genética , RNA Mensageiro/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Antígeno Sialil Lewis X , Células Tumorais Cultivadas , Fator de Necrose Tumoral alfa/genética , Fator de Necrose Tumoral alfa/metabolismo
8.
PLoS One ; 6(1): e16281, 2011 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-21283832

RESUMO

Similar to mechanisms of recruitment of activated leukocytes to inflamed tissues, selectins mediate adhesion and extravasation of circulating cancer cells. Our objective was to determine whether sialyl Lewis X modified core 2 O-glycans (C2-O-sLe(X)) present on colon and hepatic carcinoma cells promote their adhesion and invasion. We examined membrane expression of C2-O-sLe(X), selectin binding, invasion of human colon and hepatic carcinoma cell lines, and mRNA levels of alpha-2,3 fucosyltransferase (FucT-III) and core 2 beta-1,6 N-acetylglucosaminyltransferase (C2GnT1) genes, necessary for C2-O-sLe(X) synthesis, by quantitative reverse-transcriptase (RT) PCR. Synthesis of core 2 branched O-glycans decorated by sLe(X) is dependent on C2GnT1 function and thus we determined enzyme activity of C2GnT1. The cell lines that expressed C2GnT1 and FucT-III mRNA by quantitative RT-PCR were highly positive for C2-O-sLe(X) by flow cytometry, and colon carcinoma cells possessed highly active C2GnT1 enzyme. Cells bound avidly to E-selection but not to P- and L-selectin. Gene knock-down of C2GnT1 in colon and hepatic carcinoma cells using short hairpin RNAs (shRNA) resulted in a 40-90% decrease in C2-O-sLe(X) and a 30-50% decrease in E-selectin binding compared to control cells. Invasion of hepatic and colon carcinoma cells containing C2GnT1 shRNA was significantly reduced compared to control cells in Matrigel assays and C2GnT1 activity was down-regulated in the latter cells. The sLe(X) epitope was predominantly distributed on core 2 O-glycans on colon and hepatic carcinoma cells. Our findings indicate that C2GnT1 gene expression and the resulting C2-O-sLe(X) carbohydrates produced mediate the adhesive and invasive behaviors of human carcinomas which may influence their metastatic potential.


Assuntos
Carcinoma Hepatocelular/patologia , Neoplasias do Colo/patologia , Selectina E/metabolismo , Invasividade Neoplásica/patologia , Oligossacarídeos/fisiologia , Carcinoma Hepatocelular/química , Adesão Celular , Linhagem Celular Tumoral , Neoplasias do Colo/química , Epitopos/análise , Glicoproteínas/análise , Glicoproteínas/fisiologia , Humanos , Ligantes , N-Acetilglucosaminiltransferases/genética , Oligossacarídeos/análise , RNA Mensageiro/análise
9.
BMC Cancer ; 9: 79, 2009 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-19267921

RESUMO

BACKGROUND: The metastasis of cancer cells and leukocyte extravasation into inflamed tissues share common features. Specialized carbohydrates modified with sialyl Lewis x (sLex) antigens on leukocyte membranes are ligands for selectin adhesion molecules on activated vascular endothelial cells at inflammatory sites. The activity of the enzyme core 2 beta1,6 N-acetylglucosaminyltransferase (C2GnT1) in leukocytes greatly increases their ability to bind to endothelial selectins. C2GnT1 is essential for the synthesis of core 2-branched O-linked carbohydrates terminated with sLex (C2-O-sLex). Our goal was to determine the expression profiles of C2-O-sLex in the malignant progression and metastasis of colorectal adenocarcinomas. The well characterized CHO-131 monoclonal antibody (mAb) specifically recognizes C2-O-sLex present in human leukocytes and carcinoma cells. Using CHO-131 mAb, we investigated whether C2-O-sLex was present in 113 human primary colorectal adenocarcinomas, 10 colorectal adenomas, 46 metastatic liver tumors, 28 normal colorectal tissues, and 5 normal liver tissues by immunohistochemistry. We also examined mRNA levels of the enzyme core 2 beta1,6-N-acetylglucosaminyltransferase (C2GnT1) in 20 well, 15 moderately, and 2 poorly differentiated colorectal adenocarcinomas, and in 5 normal colorectal tissues by using quantitative real-time polymerase chain reactions (RT-PCR). RESULTS: We observed high reactivity with CHO-131 mAb in approximately 70% of colorectal carcinomas and 87% of metastatic liver tumors but a lack of reactivity in colorectal adenomas and normal colonic and liver tissues. Positive reactivity with CHO-131 mAb was very prominent in neoplastic colorectal glands of well to moderately differentiated adenocarcinomas. The most intense staining with CHO-131 mAb was observed at the advancing edge of tumors with the deepest invasive components.Finally, we analyzed C2GnT1 mRNA levels in 37 colorectal adenocarcinomas and 5 normal colorectal tissues by RT-PCR. Significantly, we observed a greater than 15-fold increase in C2GnT1 mRNA levels in colorectal adenocarcinomas compared to normal colorectal tissues. CONCLUSION: C2-O-sLex, detected by the CHO-131 mAb, is a tumor associated antigen whose expression is highly upregulated in colorectal adenocarcinomas and metastatic liver tumors compared to normal tissues. C2-O-sLex is a potentially useful early predictor of metastasis.


Assuntos
Adenocarcinoma/metabolismo , Antígenos de Neoplasias/metabolismo , Biomarcadores Tumorais/metabolismo , Neoplasias Colorretais/metabolismo , Neoplasias Hepáticas/metabolismo , N-Acetilglucosaminiltransferases/metabolismo , Adenocarcinoma/diagnóstico , Adenocarcinoma/genética , Adenocarcinoma/patologia , Antígenos de Neoplasias/genética , Biomarcadores Tumorais/genética , Metabolismo dos Carboidratos , Colo/citologia , Colo/metabolismo , Neoplasias Colorretais/diagnóstico , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Selectina E/metabolismo , Humanos , Imuno-Histoquímica , Fígado/citologia , Fígado/metabolismo , Neoplasias Hepáticas/diagnóstico , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/patologia , N-Acetilglucosaminiltransferases/genética , Metástase Neoplásica , Estadiamento de Neoplasias , Polissacarídeos/metabolismo , Prognóstico , Ligação Proteica , RNA Mensageiro/análise , Reação em Cadeia da Polimerase Via Transcriptase Reversa
10.
Cancer Lett ; 217(1): 105-13, 2005 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-15596301

RESUMO

The selectin family of adhesion proteins directs leukocytes in the blood to lymphoid organs and sites of inflammation, and is also thought to be involved in the dissemination of carcinomas expressing sialylated Lewis glycan structures, such as sialyl-Lewis X (sLeX). The expression of core 2 beta1,6 N-acetylglucosaminyltransferase (C2GnT) by leukocytes allows for the biosynthesis of core 2 O-glycans that when terminated by sLeX can serve as high-affinity selectin glycan ligands. In particular, the sLeX-modified core 2 O-glycan structure C2-O-sLeX has been directly demonstrated to confer significantly higher affinity selectin binding than sLeX. We have recently described the reactivity of the mAb CHO-131, which is dependent on the enzymes alpha2,3-sialyltransferase, alpha1,3-fucosyltransferase, and C2GnT, and specifically recognizes the glycan structure C2-O-sLeX. Here we examined a defined pair of colon carcinoma cell lines that are distinct in their capacity to bind E-selectin, as demonstrated by shear flow assays involving whole blood and shear stresses that occur in the microvasculature. CHO-131 demonstrated reactivity with such cancer cells, but only with the cell line that avidly attached to E-selectin. Hence, we demonstrate for the first time the detection of C2-O-sLeX on colon carcinoma cells, which, as with leukocytes, may be directly relevant to the expression of high affinity glycan ligands for the selectins.


Assuntos
Biomarcadores Tumorais/análise , Neoplasias do Colo/metabolismo , Oligossacarídeos/biossíntese , Polissacarídeos/biossíntese , Anticorpos Monoclonais , Selectina E/metabolismo , Citometria de Fluxo , Células HT29 , Humanos , N-Acetilglucosaminiltransferases/metabolismo , Antígeno Sialil Lewis X
11.
J Leukoc Biol ; 74(3): 389-94, 2003 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-12949242

RESUMO

L-selectin is expressed by leukocytes and facilitates their adhesion under flow along the walls of blood vessels. As do a variety of membrane proteins, L-selectin undergoes ectodomain shedding. Using approaches that monitor full-length L-selectin in short-term assays, it has been determined that L-selectin shedding is defective in tumor necrosis factor alpha-converting enzyme (ADAM-17)-deficient cells. In this study, we examined the steady-state levels of L-selectin on ADAM-17-deficient cells using a monoclonal antibody to the cytoplasmic region of L-selectin, which allows for the detection of total L-selectin (full-length and the membrane-associated cleavage fragment). We demonstrate that ADAM-17-deficient cells generate a 6-kDa transmembrane fragment of L-selectin. Although inducible L-selectin shedding by phorbol 12-myristate 13-acetate stimulation was not observed by these cells in short-term assays, basal turnover did occur, resulting in the production of soluble L-selectin, as determined by enzyme-linked immunosorbent assay. L-selectin turnover was greatly increased upon ADAM-17 reconstitution. Truncating the juxtamembrane region of L-selectin blocked ADAM-17-independent shedding as did a hydroxymate metalloprotease inhibitor. Together, these findings demonstrate that a metalloprotease activity separate from ADAM-17 can use the cleavage domain of L-selectin. We speculate that separate proteolytic mechanisms of L-selectin shedding may regulate distinct antiadhesive mechanisms, such as inducible shedding for the rapid dissociation of cell-cell interactions and constitutive shedding for the homeostatic maintenance of high serum levels of soluble L-selectin, a potential adhesion buffer.


Assuntos
Adesão Celular , Membrana Celular/metabolismo , Selectina L/metabolismo , Metaloendopeptidases/metabolismo , Proteínas ADAM , Proteína ADAM17 , Animais , Anticorpos Monoclonais/imunologia , Ácidos Hidroxâmicos/metabolismo , Selectina L/química , Metaloendopeptidases/deficiência , Camundongos , Testes de Precipitina , Inibidores de Proteases/farmacologia , Acetato de Tetradecanoilforbol/farmacologia , Fator de Necrose Tumoral alfa/metabolismo
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